Json conversion problems: invalid characters found - ios

Question

I am converting my array to json object, then sending it to server. But It is showing some invalid characters when i get them in server end. like '\n', & '\'.
Here is a sample of my data which i get at the server end:
('[\n "{\\"id\\":2,\\"qrCode\\":\\"KdcUfeddHpbepeXnyiKFjcfedHp\\",\\"activity\\":\\"2\\",\\"time\\":\\"64485\\",\\"image_base64\\":\\"\\/9j\\/4AAQSkZJRgABAQAA"}"\n]');
But it should look like the following:
('[{"id":2,"qrCode":"KdcUfeddHpbepeXnyiKFjcfedHp","activity":2,"time":1372757846,"image_base64":"AA\\u003d\\u003d\\n"}]');
here is the code:
-(void)setOflynData2JsonFormat{
if (!([self.getOfflineData count] == 0)) {
NSArray *array = [self getOfflineData];
for (int i = 0; i<[array count]; i++) {
uniqueId++;
NSNumber *uId = [NSNumber numberWithInt:uniqueId];
OfflineTableObject *offObj = [array objectAtIndex:i];
NSMutableDictionary *dict = [[NSMutableDictionary alloc] init];
[dict setValue:uId forKey:#"id"];
[dict setValue:offObj.qrCode forKey:#"qrCode"];
[dict setValue:offObj.offlineStatus forKey:#"activity"];
[dict setValue:offObj.time forKey:#"time"];
[dict setValue:offObj.imageData forKey:#"image_base64"];
SBJsonWriter *jsonWriter = [[SBJsonWriter alloc] init];
NSString *singleJsonString = [jsonWriter stringWithObject:dict];
NSLog(#"Json string : %#",singleJsonString);
arrayOfJsonString = [[NSMutableArray alloc]init];
[arrayOfJsonString addObject:singleJsonString];
}
NSData *jsonDataFromArray = [NSJSONSerialization dataWithJSONObject:arrayOfJsonString options:NSJSONWritingPrettyPrinted error:nil];
NSString *jsonString = [[NSString alloc] initWithData:jsonDataFromArray encoding:NSUTF8StringEncoding];
NSLog(#"jsonData as string:\n%#", jsonString);
int check = [obj sendOfflynData2Server:jsonString];
}
}
So, where is the problem? Thnaks in advance for the help.

Answer 1

The problem is that you are translating your data to JSON twice.
You first translate all your dicts to json with
NSString *singleJsonString = [jsonWriter stringWithObject:dict];
add them to an array, and then re-translate the array to JSON with
NSData *jsonDataFromArray = [NSJSONSerialization dataWithJSONObject:arrayOfJsonString options:NSJSONWritingPrettyPrinted error:nil];
So instead of producing the expected JSON output, it serialize an array of JSON strings, hence the escaping mess.
Instead, you should just add your dicts to the array, and then serialize the whole thing :
arrayOfJsonString = [[NSMutableArray alloc]init];
for (int i = 0; i<[array count]; i++) {
// snip
[arrayOfJsonString addObject:dict];
}
NSData *jsonDataFromArray = [NSJSONSerialization dataWithJSONObject:arrayOfJsonString options:NSJSONWritingPrettyPrinted error:nil];